Lake Otamangakau, “O-TA-MAN-GA-COW”. It can be an “utter bastard of a lake”, but at the same time hugely rewarding due to the sheer size and superb condition of the browns and rainbows that inhabit it. These are some of the hardest hitting, bars of chrome and bronze trout in the country and given the close proximity to Turangi and the Tongariro makes it one of the best easy access options for a chance at a North Island trophy.
MORE FROM THE MANIC GUIDE TO FLY FISHING IN TAUPO:
The ‘O, otherwise known as Ota, the Big O, Lake O or just plain old Lake Otamangakau, is located about 15-20 minutes drive south of Turangi and the bottom end of Lake Taupo on state highway 47. Just before you cross the Lake Otamangakau outlet canal and not far past the stunning views of Lake Rotoaira enroute, you’ll see a small road on the right called Access Road 5. Taking this road, past the canal gates, to the end of the sealed road will lead you to the first boat ramp which launches into the outlet canal and some great shore based fishing for anglers passing through without a boat. To access the main boat ramp and parking area, a further five minutes drive heading south, on the right you will see Access Road 4. The parking area is well signposted, from here you can also access the northern arm, and inlet canal shores by foot.
Lake Otamangakau is more of a giant pool on a small alpine stream. Existing farmland flooded in the early 70’s for hydro development in a “top-up” capacity for Lake Rotoaira. It consists of the main lake itself, an entry canal and exit canal plus the Northern Arm, a verdant wee drowned valley of sheer bliss renowned for its big trout on the fly.
The main part always has some current flow, hence why it’s sometimes like fishing in a river rather than a lake, especially after high rainfall on the mountain. This current flow is a key factor to great fishing, when no water is being released into Rotoaira by Genesis Energy, the fishing can be very tough! The ‘O is also very cold and its water quality can only be described as pristine, being mountain snow fed at high altitude.
Despite its minuscule size, it’s the second most heavily fished lake in the district next to Lake Taupo. Lake Otamangakau is also extremely shallow, with the exception of the main basin, just off the main boat ramp where it reaches depths of up to 15m, you can see the bottom in most locations. It is also very weedy, the dense forests of oxygen weed beds providing an enormous food supply for trout, whom gorge heavily on predominantly Snails, Damsel Nymphs and Bloodworms. There is also an occasional eel and lots of rarely seen Goldfish, but no smelt present. Lake Otamangakau in my mind is right up there with some some of the most magnificent scenery the North Island has to offer.
Nestled at the foot of the North Island’s iconic volcanic plateau, on a calm day (which is most days surprisingly given its elevation of 600m above sea level!) the volcanic peaks of Ruapehu, Tongariro and Ngauruhoe are so close, they seem within arm’s reach. Lake O is truly a beautiful spot, barren, windswept, freezing cold and piping hot. It also houses some of the most prolific bird populations and number of species I have ever seen!
Licence To Fly Fish
The Lake Otamangakau fishery requires nothing more than a Taupo area license to fish, administered by DOC, this license is a separate purchase to your standard Fish and Game license covering the rest of New Zealand, with the exception of lake Rotoaira, which requires a separate license yet again, so keep this in mind. Attracting anglers from all over the globe, some days it feels like you, a born and bred kiwi are a foreigner! It’s really not an easy fishery to conquer, especially for a first-time angler and it took me a painful ten years to finally crack the code, which even now (as experienced on my last trip), has me second guessing my abilities some days.
The Fly Fishing Gear
As a general rule you don't need a lot of options. Nothing more than a floating line is required for Lake O and a rod of between 9’ and 9’ 6” in length with a corresponding line weight between 5 and 7 in weight forward configuration. You often have to get quite delicate with long leaders on the large tailing browns to induce a take, at the expense of being dusted in the shallows by these huge trophy beasts. Did I mention if you land one out of three hookups, you’re doing extremely well?! This is an age old balancing act at this lake!
Reels need to hold at least 50m of backing and you’ll often see said backing on a big rainbow! Coupled with an ultra-smooth drag system, as found on all the Lamson reels, is an excellent start. If fishing solo, you will need this drag to be able to manoeuvre your boat and follow the fish at the same time, having a drag system you can reply on is paramount here.
Leader configurations need to be as long as you can comfortably get away with, as a rule, nothing under 14 feet should be used and up to 18-20 feet is the norm. Being a predominately boat access fishery means you can usually get your back to the wind to aid casting these long leaders. Our finned friends can be very leader shy, especially in calm conditions. A good fluorocarbon tippet such as Trout Hunter in 3x or 4X should stop most fish in their tracks if fishing sub-surface, and has fantastic abrasion resistance if pulled through the snags. If fishing dry / dropper rigs, a tippet material that floats and won’t sink into the weed is a better choice. The Airflo Tactical Co-polymer or EVO tippet in 3X and 4x is an excellent choice here.
The Lake Otamangakau Fly Fishing Calendar
This can be broken up roughly into two distinct seasons. Opening on October 1st each year heralds the start of the new season on the lake, some opening days it’s like a typical Auckland boat ramp on a Saturday morning in summer! Other opening days, you might be the only car in the car park?! There is no hard and fast method for gauging how busy the lake will be, but it can withstand a LOT of pressure, so don’t be put off by the crowds. There is always somewhere to post up and fish, and around 95% of anglers still choose boat access rather than the shore.
The ‘O is really best fished using a boat due to its swampy nature, and launching is available from one of two ramps described earlier. A boat, whilst not a necessity, is certainly a huge asset for getting access to the numerous shore wading spots. Kayaks, dinghies and float tubes are all perfect for the ‘O and you don’t need to own the latest $150k hardtop for success, a $1000 inflatable dinghy and a 2hp motor will do just fine!
But please be aware, this lake has some of the most dangerous wading conditions you will ever encounter. The muddy bottom has numerous bottomless holes and human-sucking silt that will catch you unawares in a heartbeat. However, shore-based angling is my personal preference at the ’O for many reasons. If you do find yourself stuck fast in the mud, try and get onto your knees to spread the load, increase your surface area and shuffle forward to firmer ground where you can stand up again. It’s a good lake to fish with a buddy for this reason, rather than solo.
October Through Until Mid February
Browns averaging around 5-6lbs congregate in the numerous shallow bays and by mid January these browns will average a whopping 6.5-9lbs average in size, some much larger again and the chance of tangling with 10-12lb fish is quite high. They present such a challenge, especially when tailing, where you can view them cruising the silty flats hovering up bloodworms in the shallows. It is arguably the most exciting form of sight fishing you can have, and it comes as no surprise that bloodworm imitations feature VERY heavily in the anglers fly box here. Also successful, is boat fishing using a drogue to slow your drift, flicking nymphs under small indicators into the numerous holes amongst the main channels. Nymphing is the most popular method at the ‘O, as it simply works!
If I’m not casting to tailing browns, you’ll find me stripping small #10 Woolley Buggers on the edges, a very physical, rewarding and extremely exciting method on the lake. The retrieve can be quite fast in a start stop fashion, and look for the telltale sign of a bow wave chasing your lure, often right to the boat and the hits can be savage! The general rule of thumb is browns in close, rainbows in the deeper water early season, but there are couple of factors that have a huge bearing on your success here. The first being the lake level. Interestingly the lake fishes best when it is coming down from being high, not the other way around which is usually the norm for lake fishing. This is especially relevant to shore based fishing. In most lakes, rising levels put the fish into a frenzy, not here and I have never really understood why it is like this. You can view the lake levels through the Genesis website here.
However, with the lake being so small and shallow, level fluctuations can go and down by up to several feet in a day! The second factor for success, and the main contributing factor to a blank day is WIND!! which I’ll explain further in the WEATHER section below.
One of the other methods I favour, and one which is not often used, is targeting cruising fish with a dry dropper rig, this has proven absolutely deadly on both species over the last 10 years, often a dropper of no more than 100mm is required, as the fish will be cruising the shallow weed edges. If it is hot, which it often is in the summer months, great success can be had drifting massive dry fly imitations such as Hoppers and Cicada’s in the cooler inflow water where the canal enters the main basin of the lake. The strikes are often savage and usually from rainbows between 5 and 7lbs.
If a fish does go into the weed on hookup, do NOT let your line go slack which is commonly touted advice, this never works! The fish will just bury themselves deeper in the weed and you risk killing the fish through suffocation. Maintain a CONSTANT high pressure on the fish, each time they kick, you will gain a littler ground, and after several minutes you’ve extracted the fish – it works almost every time, but the pressure has to be sustained, don’t give an inch of slack!
Mid February Through To May 30th
Late season heralds the start of rainbow time! The browns have usually departed to do their thing by early April and the open-water rainbows will feed ravenously on anything that moves in preparation for spawning, late season can be a great time to fish the lake, usually devoid of anglers, you can have the lake to yourself for days on end until the duck shooters arrive on May the 1st. it’s best to give the lake a miss for the first week following May 1 for obvious reasons… and the lake closes for the season on May 30th each year. Most success can be had in the deeper channels at this time of year, casting lightly weighted flies on long leaders around the weed edges of the main channels and basins.
There is a strange phenomenon that occurs here late season where large pre-spawning jacks will take to the air in magnificent displays of aerial acrobatics for absolutely no reason at all, other than I suspect to get the attention of marauding females to pair up with. These fish have no problem clearing a 2m jump time and time again, it’s quite an impressive feat to be a spectator on!
This is a big factor. The crappier wetter and windier the weather at Lake Otamangakau, the better the fishing! Unfortunately, calm days are the norm here which is surprising given the lakes altitude and open tussock-basin nature. For any amount of success at the ‘O you need one single component… WIND!!!! Get a wind ruffled surface, no matter what the weather, and you can guarantee success. Calm? Forget it, you will have your work cut out! If you can manage to stick out rain squalls and freezing temperatures, you will have a ball! This is an excellent localised weather resource to stay abreast of the weather forecast at Lake Otamangakau.
Where To Fish - The Mates Map!
So above is a basic summary of how the lake works, and you can probably gather by now it can be a darn right HARD lake for a newcomer. So, a few mates and I have pooled together our extensive knowledge of over 30 years fishing the lake to present the Lake Otamangakau Mates Map.
This is a basic overview of where to fish and when and what methods to use. These are just the locations we have favoured over the years and the naming protocols should be taken as simply a bit of fun. Each location has a corresponding description of methods and flies that work, but I will also give you a run down on successful patterns we have found invaluable over the years below.
So get out and try this magnificent location, if big powerful trout are your thing in pristine environments, or you are a die-hard river angler looking for something different? This map will help hugely. The Big ‘O has a special place in so many anglers’ hearts, once you fish it, you’ll be hooked for life!
If that's not enough to get you fired up to make Lake Otamangakau numer one on your "next mission list" then just watch this video called "Chasing Tail" for a visual feast of what this Lake has to offer.